1. Field of the Invention
The present invention relates, in general, to digitized picture data processing systems and is particularly directed to a mechanism for controlling the manner in which digitized pictures are to be accessed from a digital database for presentation by a picture playback device.
Digital imaging systems, such as those employed for converting still color photographic film (e.g., 35 mm) pictures into digital format for storage in a digital database and subsequent playback, as by way of a color television monitor, customarily encode the output of an opto-electronic film scanning device to some prescribed resolution and store the encoded picture in an associated database as a respective picture file. When it is desired to display a particular stored picture, the contents of the respective addresses of the database in which the digitized picture has been stored are read out and coupled to display driver circuitry for energizing corresponding pixels on the TV monitor.
Because each frame of a typical roll of 35 mm film has different horizontal and vertical frame dimensions, for example, a dimension of 36 mm in the horizontal direction, parallel to the lengthwise direction of the film, and a dimension of 24 mm in the vertical direction, orthogonal to the lengthwise direction of the film (a horizontal:vertical aspect ratio of 3:2), a photographer often rotates the camera ninety degrees about the lens axis in order to capture a subject in what is conventionally referred to as a `vertical` condition. Since the digitizing mechanism that scans the film strip digitizes each frame as though it contains a `horizontally shot` picture, then, when a `vertically shot` picture is displayed, it will be rotated unless the recording and playback system has been designed to accommodate vertical pictures.
2. Description of the Related Art
One conventional approach to handle the problem, similar to that described in the U.S. Pat. No. to Ohm, 4,641,198, is to rotate those film frames which contain vertical pictures by ninety degrees before scanning, and to fill in the left and right sides of the picture with a uniform `border` color (e.g., black). Although this scanning method will provide the proper orientation of the displayed picture, it suffers from two drawbacks. First, the actual scanning mechanism must be modified to effect a rotated scan of the vertical pictures. This is conventionally accomplished by physically reorienting the film by ninety degrees and changing the lens magnification of the scanning device by an amount related to the frame aspect ratio. Secondly, since side borders, which contain no useful information in terms of the captured picture, are also recorded, some of the information storage capacity of the recording medium is wasted. A second solution to the problem is to rotate the display device, which is obviously impractical in many applications.
A third solution is to allow for different picture orientations to be stored, together with digital control data indicative of the orientations of the pictures, and to employ a picture playback device designed to read the orientation control data to properly orient the pictures on playback. Some conventional computer picture file formats, for example, the Tag Picture File Format (TIFF), Revision 5.0 , developed jointly by Aldus Corporation, Seattle, Wash., and Microsoft Corporation, Redmond, Wash., and described in "An Aldus/Microsoft Technical Memorandum, Aug. 8, 1988, include the provision for an optional "tag", which can be used to indicate the orientation of the picture. Page 25 of this document describes the TIFF `orientation tag`, which can have eight different values, indicating whether the zeroth row and zeroth column of the pixel data matrix represents the top and left, top and right, bottom and right, bottom and left, left and top, right and top, right and bottom, or left and bottom of the visual picture, respectively. However, the Aldus document further states that such a field is recommended for private (noninterchange) use only. The default condition, where the zeroth row represents the visual top of the picture, and the zeroth column of the pixel data matrix represents the visual left hand side of the picture, is recommended for all non-private applications, including those involving importing and printing. Thus, the TIFF orientation tag is never used to re-orient for display, pictures which have been stored in different orientations in a picture database.
In addition to the problem of different picture orientations, captured pictures may have different aspect ratios. For example, dedicated use panoramic cameras, such as the Kodak Stretch (TM) camera have an aspect ratio of 3:1 which is considerably wider than the above-referenced 3:2 aspect ratio of conventional 35 mm cameras. Other camera types, such as those which employ 126 type film also have aspect ratios other than 3:2.